Temperature testing machine

air flowflowcomputer-controlled

Overview
For aqueous droplet inhalers (ADIs) and nebulisers, solvent evaporation from deposited droplets—exacerbated by the thermal mass of the impactor—can reduce droplet size and produce artificially low aerodynamic particle size distribution (APSD) measurements. Cooling the impactor to approximately 5°C is the recommended mitigation to limit evaporation and preserve measurement integrity for APSD testing of Soft Mist Inhalers (SMIs).

Key points

• Evaporation on impactor stages biases APSD results toward smaller particle sizes.
• Mitigation: cool the impactor to ~5°C to minimise solvent loss during sampling.
• ADIs (aqueous droplet inhalers) are treated as active devices for APSD testing.
• Recommended flow rates: ACI = 28.3 L/min; NGI = 30 L/min for ADI testing.

Equipment & system components (featured / relevant)

• Mouthpiece Adapter
• NGI Induction Port
• Next Generation Impactor (NGI)
• BAC 100i Breath Actuation Controller
• Low Capacity Vacuum Pump LCP7
• Flow Rate Sensor (FRS)
• NGI Cooler™ (impactor cooler to avoid evaporation)
• NGI Cooler™ Shelf
• NGI Cup Rack / NGI Carrying/Washing Rack
• Internal/External Filter Holder
• DFM 2000 Flow Meter
• High Capacity Vacuum Pump HCP7
• Inhalytix®+ APSD Data Analysis Software

Applications
APSD testing of Soft Mist Inhalers (SMIs) to ensure accurate aerodynamic particle size measurement in product development, regulatory submissions and comparative studies. Proper impactor cooling and selection of impactor type and flow rate are essential to maintain valid, reproducible APSD data.

Notes on measurement practice

• Consider the thermal mass of the impactor and the potential for solvent evaporation when testing aqueous-based soft mist or droplet inhalers.
• Using cooled impactors prevents solvent loss on stages and avoids a bias toward smaller measured droplet sizes.
• Select flow rate consistent with impactor type and device classification: ACI 28.3 L/min; NGI 30 L/min for ADIs.

caractéristiques / spécifications techniques

• Recommended impactor temperature: approximately 5°C to reduce droplet evaporation.
• Recommended flow rates for ADI testing: ACI = 28.3 L/min; NGI = 30 L/min.
• Device classification: ADIs treated as active devices for APSD testing.
• Typical system components: NGI, NGI Induction Port, NGI Cooler™, flow controllers/sensors, vacuum pumps (LCP7 / HCP7), mouthpiece adapters, cup racks and filter holders.
• Data analysis: Inhalytix®+ for APSD data processing and reporting.